Controlling Entanglement by Quantum-Jump-Based Feedback

We describe how feedback methods can be implemented to produce and stabilize entangled states of two atoms inside a cavity. Feedback control is used to engineer an effective environment dynamics, such that the entangled state to be protected is a steady state of the system. The control strategy is therefore robust with respect to external noises and fundamental decoherence sources, as spontaneous emission, for example. We also show that the scheme is mostly insensitive to practical imperfections, as detection inefficiencies and laser fluctuations.